Cable valley filler



July 26, 1966 F. HIRSCH 3,263,024

CABLE VALLEY FILLER Filed June 15, 1964 WAX DISPERSION SPRAYED CREPEDPAPER I I 28 I CREPED PAPER INVENTOR I LLMA, QM MAM ATTORNEYS.

United States Patent 3,263,024 CABLE VALLEY FILLER Felix Hirsch, CambriaHeights, N.Y., assignor to General Cable Corporation, New York, N.Y., acorporation of New Jersey Filed June 15, 1964, Ser. No. 375,235 8Claims. (Cl. 174-116) This invention relates to improvements in electriccables and more particularly to low voltage cables that have waterrepellant paper fillers in the valleys between insulated conductors.

Multiple conductor electric cables commonly have the valleys between theinsulated conductors filled with paper, jute, or other material toprovide a round contour over which the outer covering or sheath of thecable is applied. It is important, however, to prevent the paper, juteor other filler material from acting as a wick and conveying moisturelongitudinally of the cable. Where paper has been used as the tiller ithas been conventional pract-ice to prevent such wick action by using arelatively hard paper which is immersed in wax prior to being twistedinto a filler strand or cord.

Such twisted paper filler strands are hard and have a limiteddeformability, and in order to provide a substantially round contour forthe cable it often is necessary to use a number of them. It has beennecessary to have a number of different sizes of fillers for differentsizes of cables, and for cables having different numbers of conductorsand resulting differences in the shapes and sizes of their valleys.

It is an object of this invention to provide an improved cable of thetype having a paper filler in the valleys and an improved method ofmaking such cable. It also is an object of this invention to provide animproved valley filler and method.

Contrary to the usual practice, this invention uses creped paper for thevalley filler instead of kraft paper. Creped paper has been consideredunsuitable for such use in cables where wick action must be avoided. Infact, creped pap-er has been used in the past as a valley filler only inoil-filled cables where the wick action was desirable, as in theBranthwaite Patent 1,886,786, November 8, 1932, where it is explainedthat with creped paper the oil becomes more quickly distributed throughthe cable. In cables that are filled with insulating oil or other fluidinsulation it is known to provide a channel in the cable to facilitatethe fiow of the oil or other fluid lengthwise through the cable.

The cable with which this invention is concerned involves just theopposite considerations. Travel of moisture or other liquid, if it getsinto the cable, must be prevented or limited. The valley fillers must beconstructed of material which will not operate with a wick action todistribute moisture length-wise within the cable. Creped paper cannot beimmersed in wax and then gathered to form valley fillers in the way inwhich hard kraft papers are treated because the creped paper will takeup an excessive amount of wax and it is of toolow tensile strength to befor-med into a suitable cord or strand for use in a valley of anelectric cable.

This invention involves the novel concept of using creped paper which ismuch lighter, more flexible, and more resilient than ordinary kraftpaper as a valley filler and imparting the necessary water repellantquality to the creped paper by applying wax which is sprayed onto thepaper instead of immersing the paper in wax. By this Patented July 26,1966 ice method the amount of wax on the paper is limited and there isno filling of the small crepe valleys of the creped paper with wax.However, the wax sprayed onto the surface of the paper covers the entiresurface and after the paper has been gathered and twisted into a fillerstrand or cord the wax penetrates the paper and is present in sufficientquantity to prevent wick action. It has been found that the wax can bemost easily applied in the necessary small quantity by spraying it ontothe creped paper in the form of a water dispersion before the paper isfolded or gathered. In the preferred embodiment of the invention theamount of wax applied is approximately three to four percent of theweight of the paper with the wax on it, after the water has evaporated.

The invention has several important advantages. One is that the crepedpaper has added volume and that a 16 lb. creped paper can be used inplace of 30 to 40 lb. kraft paper fillers which are not creped. Anotheradvantage is that the amount of wax used on the creped paper is muchless than that used on the kraft paper which has been immersed in a waxbath prior to twisting it into a cord or strand. This results in asubstantial saving in material which makes the cable less expensive tomanufacture and which also makes the cable lighter in weight. Forexample, one cable valley filler made in accordance with this inventionweights 5 lbs. per thousand linear feet as compared with 9.6 lbs. perthousand linear feet for comparable conventional kraft paper valleyfiller.

In addition to the advantages of being less expensive and lighter inweight, the electric cable made in accordance with this inventionactually is better cable. The valley fillers made of the creped paperare soft and more forma-ble than the valley tillers made of the hardkraft paper immersed in a wax bath. Because of this softer and moreforma-ble characteristic the assembly of insulated conductors and valleyfiller-s takes the desired round shape more easily and forms a smootherand better final product.

Other objects, features and advantages of the invention will appear orwill be pointed as the description proceeds.

In the drawings, forming a part hereof, in which like referencescharacters indicate corresponding parts in all the views:

FIGURE 1 is a diagrammatic view showing a multiconductor electric cablewith the outside sheath removed for part of the length and with theconductors and valley filler-s separated to show the various parts ofthe assem- FIGURE 2 is an enlarged sectional view taken on the line 2-2of FIGURE 1; and

FIGURE 3 is a diagrammatic view showing the way in which the fillermaterial is made in accordance with this invention.

In the illustrative embodiment of this invention an electric cableindicated generally by the reference character 10 includes threeelectrical conductors 11, 12 and 13 surrounded by individual walls ofsuitable electrical insulation 15 and enclosed within an outer sheath 17of electrically insulating material. The outer sheath 17 may bemoistureproof or waterproof for use in underground installation. Theinsulated conducbors 11, 12 and 13 are located adjacent to one anotherand preferably touch one another along lines of adjacency designated bythe reference characters 21.

There are several valley fillers 23 located in each of the valleysbetween the insulated conductors and out- Wardly of the lines ofadjacency. These valley fillers 23, originally round or oval in shape,are distorted as necessary to fill the valleys and make the assembly ofthe insulated conductors and the valley fillers substantially circular,so as to fill the space within the sheath 17.

While it is desirable that the valley fillers distort and compress tothe exact cross section of each valley, it is not essential that theyfill the valley all the way to the line of adjacency 21 because thefillers pressing against each other and against the sides of insulatedconductors will form a barrier to the entrance of any Water into theinterior of the assembly even though they do not reach all the way tothe vertex of the angle formed by the insulated conductors at the pointsof adjacency. However, it is desirable that the fillers should reachinto the vertex of these angles at frequent locations so as not to leavean unobstructed passage lengthwise of the cable for the travel of anymoisture which may enter at the end of the cable. The actual crosssection of each of the valley fillers 23, in the completed assembly,will vary somewhat at different locations along the length of the cabledepending upon how they are pressed into the valleys and their relationto one another at the time of distortion into the space which they areto fill.

The valley fillers 23 are originally round or oval in cross section andsince there are limits to which the shape can be distorted it is usualto employ a plurality of fillers in a valley so as to fill the valleywith less distortion of the shapes of the individual fillers. Withconventional fillers it has been the practice to employ nine differentsizes of fillers for various valleys on different sizes of cable, butwith this invention it is sufficient to have only three sizes offillers. This saving is because of the greater softness andcompressibility of the creped paper fillers.

Comparative tests have been conducted on the lightly waxed, creped paperfiller of the present invention and heavily waxed kraft paper fillerwidely used in cable manufacture. The following table lists dataobtained using a Randall Stickney gage with a in. diameter pressure footat room temperature and measuring the deformation seconds after theapplication of the load:

2. Dimensions, approximate:

Kraft-.20 x .13. creped-.23 x .10.

The above data indicates that the lightly waxed creped paper fillerdeforms about twice as much as the more heavily waxed kraft paperfiller.

FIGURE 3 is a diagrammatic showing of the way in which one of thefillers 23 is manufactured. A strip of creped paper 28, for example 5inches wide is sprayed with a water dispersion of wax from a spraynozzle 30. The dispersion is preferably applied as a fine mist or fogand it is, of course, desirable to apply as little Wax as necessary foradequate water repellency.

An anionic dispersion of paraffin wax such as is avail- .able from NopcoChemical Company is suitable, for example. The wax itself may be thesame as the wax used in treating kraft paper by the immersion procedure.The temperature at which the dispersion is sprayed onto the creped papershould be such as to prevent the paraffin from solidifying andseparating. This temperature may be room temperature, but it has beenfound that a temperature of about 180 F. gives very satisfactoryresults. As previously explained, it has been found that wax applied bya fine spray to the surface of the creped paper is in suflicientquantity if the weight of wax is between three and four percent of theweight of the combined wax and paper after the water of the dispersionhas evaporated. The dispersion partially penetrates the paper as it issprayed on. This does not leave the paper covered with a continuouscoating of wax and substantial quantities of the interstices of thecreped paper are not filled With wax. The paper is gathered and twistedWhile wet to form a cord 32, as indicated in FIGURE 3. The amount oftwist may vary, but about six turns per foot gives a satisfactoryproduct. This causes further penetration and distribution of the waxinto the paper and over its surface. The contact between wax coveredareas of the gathers and adjacent areas form barriers which effectivelyclose off against moisture transfer any longitudinally extending openspaces which may exist within the twisted cord 32.

The creped valley fillers of the present invention may be made from 16pound ream weight paper as compared with 30 to 40 pound kraft papersrequired [for impregnated fillers. It has been found that valley fillersmade as herein described are adequately water repellant and will notpermit water to travel along their length by wick action. More wax canbe used, but it is unnecessary and adds both cost and weight. In thecreped paper fillerof this invention the wax comprises 3 to 4% of theweight of the filler, whereas in the Wax impregnated kraft paper the waxcomprises 15 to 20% of the Weight of the filler. Because of the lowerweight and the greater compressibility of the creped paper filler theweight of the filler per foot of cable is substantially reduced, forexample from 9.6 pounds to 5 pounds per 1000 feet in one cable.

This invention may be variously modified and embodied within the scopeof the subjoined claims.

What is claimed is:

1. An electric cable construction including a plurality of conductorseach of which is covered with a layer of electrically insulatingmaterial, the conductors being located adjacent to one another and withvalleys extending outward from the lines of adjacency of the insulatedconductors, fillers in the valleys including cords made of creped paperhaving wax on the surface thereof and at least some of the intersticesof the creping being free of wax with resulting saving in weight andimproved flexibility of the filler, and an outer sheath covering theassembly of conductors and valley fillers and holding the assemblypacked together to a smooth rounded contour.

2. The electric cable construction described in claim 1 characterized bythe creped paper being twisted to a relatively loose and compressiblecord.

3. The electric cable construction described in claim 2 characterized bythere being at least three conductors and there being a plurality offillers in each of the valleys.

4. The electric cable construction described in claim 3 characterized bythe creped paper having sufficient wax to prevent each filler fromacting as a wick for moisture, and the sheath being of waterproofmaterial for use underground.

5. The electric cable construction described in claim 4 characterized bythe wax on the creped paper constituting approximately three to fourpercent of the filler, by weight.

5 6 6. The electric cable constr ction described in claim 5 ReferencesCited by the Examiner ggatlrlacgfigltsi by the fillers being dry andclosely packed UNITED STATES PATENTS 7. A lightweight water repellantcable valley filler 809,312 5/ 1904- Lougee 156-55 comprising crepedpaper having wax on the surface of 5 1,282,208 6/1917 Fisher 15655 thepaper and at least some of the interstices of the 2,185,558 2/1935Lunsford 174-116 creped paper free of wax, the paper being gatheredtrans- 2,230,888 7/ 1938 Lamela 174-116 versely and having a crosssection of a cord.

8. The lightweight valley filler described in claim 7 LEWIS H. MYERS,Primary Examiner. characterized by the paper being twisted to hold the10 ROBERTK SCHAEFER Examiner gathers against separation and to maintainthe diameter of the cord. H. HUBERFELD, Assistant Examiner.

1. AN ELECTRIC CABLE CONSTRUCTION INCLUDING A PLURALITY OF CONDUCTORSEACH OF WHICH IS COVERED WITH A LAYER OF ELECTRICALLY INSULATINGMATERIAL, THE CONDUCTORS BEING LOCATED ADJACENT TO ONE ANOTHER AND WITHVALLEYS EXTENDING OUTWARD FROM THE LINES OF ADJACENCY OF THE INSULATEDCONDUCTORS, FILLERS IN THE VALLEYS INCLUDING CORDS MADE OF CREPED PAPERHAVING WAX ON THE SURFACE THEREOF AND AT LEAST SOME OF THE INTERSTICESOF THE CREPING BEING FREE OF WAX WITH RESULTING SAVING IN WEIGHT ANDIMPROVED FLEXIBILITY OF THE FILLER, AND AN OUTER SHEATH COVERING THEASSEMBLY OF CONDUCTORES AND VALLEY FILLERS AND HOLDING THE ASSEMBLYPACKED TOGETHER TO A SMOOTH ROUNDED CONTOUR.